Current responsive acceleration control for electric motors



June 3, 1952 E. BATTILANA 2,598,659

CURRENT RESPONSIVE ACCELERATION CONTROL FOR ELECTRIC MOTORS Filed Feb.16. 1949 Patented June 3, 1952 CURRENT RESPONSIVE ACCELERATION CONTROLFOR ELECTRIC MOTORS Emilio Battilana, Genoa-Cornigliano, Italy, as-

sign'or, by me'sne assignments, to Soc. Per Azio'ni StabilimentiElettromeccanic'i Riuniti Ansal'do San Giorgio, Genoa, Italy, a companyof Italy Application February 16, 1949, Serial No. 76,674 In ItalyFebruary 23, 1948 4 Claims. I

In an electric traction equipment, the manner of producing the sequenceof remote control switchings', called telerupters, for cutting outresistances is well known, as efiected by means of an auxiliary motorwhich drives a cylinder con trolling in turn the remote switches and ofa relay, called acceleration relay, which for a given value of currentis set into a certain operative position and, responsive to the openingof electric circuits, stops the auxiliary motor and consequently thesequence of remote control switching.

During the starting period of the motor, the current therethrough isreduced and thereby the acceleration relay is caused to take anotheroper ative position which, as a result of electric circuit connections,sets the auxiliary motor in motion again, thereby closing the sequenceof the remote control switching for starting again.

Sometimes it is desirable to assign several calibrations to theacceleration relay and therefore it happens that during the startingoperation, in passing from one calibration value to another, there is nogradual passage between the two or more values of the accelerationrelatingto the two or more values of calibration current.-

Accordingly, it is an object of the present invention to eliminate thisdrawback and to enable the accomplishment of a starting which graduatesthe increase in acceleration between certain limits.

A further and more particular object is to enablea starting havingaconstant variation of acceleration as a function of time. 7 v v In thesheet of drawings having a single figure hereto annexed there isillustrated, only by way of example, an embodiment of a device accordingto the present invention. I

The device heredisclosed in effect very advantageously substitutes forthe said auxiliary motor, the control cylinder and the accelerationrelay andthe several calibrations as known.

Referring to the drawing, which is a circuit diagram, there is shown anacceleration relay having two connected magnetic circuits constituted bycores HI, H2 and I I3} the yoke H4 and armature I I5 slightly biased byspring I' I6 in the position shown in the figure. Said armatureoscillating on core H2 operates the closing and opening of contacts H1and H8 alternatively. On the: cores III and H3, there are two coppertubes, H9 and I20, constituting two short-circuit windings which serveto delay the release of armature H5 by a predetermined and constant timevalue. The voltage coil I 2| acts to generate a magnetic flux in thecircuit composed by' cores II I and H2 closed by yoke H4 and thearmature I I5. Coil I22 acts similarly respecting the circuit composedby cores H2, H3, yoke H4 and armature H5.

Coil I23 through which the traction current passes, has the function ofgenerating a magnetic flux in both circuits, one circuit including elements HI, H5, H2 and H4, and the other including elements H2, H5, H3 andHA. In these magnetic circuits there will circulate two fluxes of widelydifferent values, owing to the differences in the values of theirrespective reluctances. If the armature be considered in the positionshown in the figure and the 0011 I2! be fed, if now this feeding beinterrupted and the voltage coil I22 be fed, core I I3 may attractarmature I Ilionly after the retardation time caused by tube H9 haselapsed, if the current value in current coil I23 will have such a valueas to allow it, because the flux generated by this coil willprevailingly cir culate in the circuit consisting of elements H2, H5,III and H4 which will be opposed to the armature motion. The result isthat the armatur'e oscillations are under the control of the tractioncurrent and, therefore, of the car load. The stabilization of thecurrent increase is of importance in the operation of the subdivisionsof the starting resistance I24.

The reaction moment caused by spring I I6 has a negligible value,especially because there isa change of sign when core I I I attracts thearma ture, which gives rise to a slight inequality of time in theoscillation of the armature.

Consider now the description of the starting of a trackless trolley car,the equipment of which is constituted by a continuous current tractionm'otor I26 with series excitation I25, a starting resistance- I24,control apparatus III-J23, a remote'control line switch I, to whichcorresponds contacts II, I2 and I3, a set of remote control sequenceswitches 29 wherein for switch 2 there corresponds contacts 2I2B, forswitch 3 there corresponds contacts 3'I-'36, and so on. Said set ofremote control switches is divided into two groups which are operated bycross-coupled contacts in connection with feeding and locking of coilsI2I and I22 alternatively. The main operating organ is the pedal whichas shown in the diagram is represented by contacts ll" to IX. Said pedalhas the following positions:

State of rest, by whichall circuits are open;

First position, by which the motor runs on resistance I24;

II to IX positions, by which the exclusion of the starting resistancetakes place.

Starting the car In the first position of the pedal, it closes contact Ithereby feeding the remote control switch I of the line; the lattercloses contacts II and I2 putting motor I25 in circuit with the network,and closes contact I3 preconditioning the feeding of remote controlswitch 2. Motor I26 starts through the whole series resistance I24.

Suppose now the case in which the pedal is put directly into the IXposition and contacts 0 and II to IX are closed; contacts II to IXprecondition the circuit for the feeding of remote control switches 25.

By closing contacts with O, coil I22 is fed and core H3 will be able toattract armature H only when the traction current in coil I23 is equalto, or smaller than, the calibration value.

When core H3 is able to attract armature H5, contact I I8 will close andfeed remote switch 2; the latter operating closes contact 2I excluding aportion of the starting resistance I24, it opens contact 24 and closescontact 25 feeding itself therethrough, it closes contact 26reconditioning the circuit to feed remote switch 3, it

opens contact 22 interrupting the feeding to coil I22, it closes contact23 thereby feeding coil I2I. If, by the exclusion of the portion of thestarting resistance I24, a rush of current is produced in the tractioncircuit and, therefore, in coil I23, which is of a higher value thanthat of the calibration of the device, it will have the result ofholding armature H5 in contact with the core H3; when said rush ofcurrent shall have fallen to the calibration value, armature I I5 willbe released by core H3 and attracted by core III; this, however, willhappen if the rush of current shall have the same or a longer durationthan the retardation produced by popper tube I; otherwise, this timewill prevail over the first mentioned time; to insure that the tractioncurrent be established sooner than the current in coils I2I and I22, asuitable arrangement of contacts of the remote switches is provided.When armature H5 has been released by core H3 and attracted by core III,contact H8 will open and nothing will happen, because switch 2 has beenlocked up through contact contact II! will close and feed remote controlswitch 3; this switch 3 will close some of its contacts and open othersin accordance with the analogous function of these contacts in case ofremote control switch 2. This will be repeated for remote switches 49,while armature H5 will continue to oscillate with a minimum time periodequal either to the retardation caused by the copper tube H9 and I25, orto the duration of the rushes of traction current produced by theexclusion of the portions of starting resistance I24.

By the feeding of remote control switch 9, the exclusion of startingresistance I24 is brought to an end and contact 92 is open; the armatureoscillations are definitely stopped, for contact 82 has been alreadyopened by remote control switch 8 and the starting operation may beconsidered ended.

If the pedal had not been pushed all the way down, but, for instance,only so far as to close contact IV, the exclusion of resistance I24would have stopped with the closing of remote switch 4, because remotecontrol switches 5-9 are operated by contacts V to IX which are stillopen. The armature has stopped at the position illustrated in thefigure, because remote switch 4 has opened contact 42 and closed contact43; in

due course, 4H will have attracted armature H5 and, consequently,contact H! has been closed; but the latter cannot feed remote switch 5because contact V is open. By pushing the pedal still farther, thealready described sequence will be resumed, with the possibility ofstopping at any predetermined position.

stoppage of car By bringing the pedal from position IX to that of rest,contacts IX to I in decreasing order are opened, while contact 0 openstogether with contact 2, so that the restoration of remote switches 9 toI takes place by steps, thereby putting the starting resistance I24 intocircuit as far as the opening of remote line switch I which breaks thefeeding of traction motor I26. During the restoration of remote switches9-I, armature H5 oscillates while following them, although it is notconnected, and it could even lose some cycles. If when letting the pedalcome back it is stopped in an intermediate position, motor I25 will goon running with the corresponding portion of resistance left in circuit;furthermore, it will be readily understood that armature H5 has beenplaced in such a position that the renewal of a starting operation ispossible by pushing the pedal instead of drawing it back.

Braking of the car The control device for braking operates in a similarmanner to that of the starting; for the sake of simplicity thearrangement as disclosed has not been provided with the apparatuscomprising the braking circuit.

Although for descriptive reasons, the present invention is based on whathas been shown and described by way of example, it is obvious that manymodifications and additions may be included in the embodiment of theinvention, all of them nevertheless being based on the fundamentalprinciples of the invention, as defined in the appended claims.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is too be performed, I declarethat what I claim is:

1. In an oscillatory device for controlling the starting of electricmotors, the combination of a control circuit having two series ofcontrol devices inserted therein, each said control device having twocontact elements, a bar of magnetic material mounted for oscillatorymovement about a pivot, a contact carried by each end of the bar,respective cooperative contact plates each having circuit connections toone of the contact elements of one series of control devices for saidstarting, a magnetic bridge the two ends of which are located inoperative relation to the respective ends of said bar, like voltagecoils carried on each of said bridge ends respectively, one end of thetwo coils being connected to one pole of the feeding line of the motorand of the control circuit, the other ends of said coils being connectedto other contact elements of said control devices and thereby to theother pole of said feeding line.

2. A device according to claim 1, wherein the said magnetic bridge isE-shaped and includes a central core, the upper end of which ismagnetically connected to the said magnetic bar at said pivot, saidcentral part having a current coil in series with the motor circuit.

3. A device according to claim 2, wherein the respective extreme ends ofsaid magnetic bridge have short-circuiting sleeves and the said cur-UNITED STATES PATENTS rent coils are so energized that each causes theNumber Name Date flux in the same direction in the central core.1,037,433 Carichofi Sept 3, 1912 4. A device according to claim 1,including 2L 1 0 9 2 Carichofi Nlar. 10 191 tensile spring connected atone of its ends to a 5 2,073,382 Tmfimov Man 9, 1937 fixed point and atits other end to the oscillatory 2,455,060 Holmes Nov. 30, 1948 magneticbar at a point distant from said pivot.

EMILIO BATTILANA.

REFERENCES CITED 10

